bmp 双线性插值_C/C++ BMP图像的放大缩小(双线性插值)及彩色转黑白
时间: 2023-11-03 14:27:25 浏览: 155
好的,我了解了您的问题。下面是关于 BMP 图像的双线性插值放大缩小及彩色转黑白的 C/C++ 实现方法。
1. 双线性插值放大缩小
双线性插值是一种常见的图像放大缩小算法,其基本思想是通过在原图像上进行采样,然后根据采样点周围的像素值计算出目标图像上对应像素的值。
具体实现步骤如下:
1)计算出目标图像上每个像素在原图像上对应的采样点坐标;
2)根据采样点周围的像素值,计算出目标像素的值。
下面是 C/C++ 的实现代码:
```
void BilinearInterpolation(unsigned char* srcData, unsigned char* dstData, int srcWidth, int srcHeight, int dstWidth, int dstHeight)
{
int x, y, k;
float xScale = (float)srcWidth / (float)dstWidth;
float yScale = (float)srcHeight / (float)dstHeight;
float xDiff, yDiff;
int x1, y1, x2, y2;
float v1, v2, v3, v4;
for (y = 0; y < dstHeight; y++)
{
for (x = 0; x < dstWidth; x++)
{
xDiff = (x + 0.5) * xScale - 0.5;
yDiff = (y + 0.5) * yScale - 0.5;
x1 = (int)floor(xDiff);
y1 = (int)floor(yDiff);
x2 = (int)ceil(xDiff);
y2 = (int)ceil(yDiff);
if (x1 < 0) x1 = 0;
if (y1 < 0) y1 = 0;
if (x2 >= srcWidth) x2 = srcWidth - 1;
if (y2 >= srcHeight) y2 = srcHeight - 1;
v1 = srcData[y1 * srcWidth + x1];
v2 = srcData[y1 * srcWidth + x2];
v3 = srcData[y2 * srcWidth + x1];
v4 = srcData[y2 * srcWidth + x2];
for (k = 0; k < 3; k++)
{
dstData[y * dstWidth * 3 + x * 3 + k] = (unsigned char)(((v1 * (x2 - xDiff) + v2 * (xDiff - x1)) * (y2 - yDiff) +
(v3 * (x2 - xDiff) + v4 * (xDiff - x1)) * (yDiff - y1)) / ((x2 - x1) * (y2 - y1)));
}
}
}
}
```
2. 彩色转黑白
彩色转黑白是一种将彩色图像转换为灰度图像的常见方法。其基本思想是通过将每个像素的 RGB 值取平均值,得到对应的灰度值。
下面是 C/C++ 的实现代码:
```
void ColorToGray(unsigned char* srcData, unsigned char* dstData, int width, int height)
{
int i, j, k;
unsigned char r, g, b, gray;
for (i = 0; i < height; i++)
{
for (j = 0; j < width; j++)
{
r = srcData[i * width * 3 + j * 3];
g = srcData[i * width * 3 + j * 3 + 1];
b = srcData[i * width * 3 + j * 3 + 2];
gray = (unsigned char)((r + g + b) / 3);
for (k = 0; k < 3; k++)
{
dstData[i * width * 3 + j * 3 + k] = gray;
}
}
}
}
```
希望我的回答对您有所帮助!
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